Description of prior art
As is known, in valve construction it is necessary in many cases to connect the constituent parts of the valves to one another. This is traditionally effected by screws or by means of deformable rivets which can also be heated to facilitate the deformation. Both types of connexion are relatively expensive or have other disadvantages. The screw connexions require machined threaded bolts and nuts, which in turn require space, whereas the simpler rivet connexions require for their manufacture the application of frequently substantial upsetting forces, as a result of which the valve parts resting thereon can be adversely affected. If the rivets are used in the heated state, the parts coming into contact with them can be damaged by the heating, for example with respect to the material hardness.
A valve with a central bolt for connecting the valve parts is known from AT-PS 242 281. The part of the central bolt, projecting beyond the catching means or the valve seating, and the associated nut require additional space in the cylinder head. Somewhat less space is required by the design according to U.S. Pat. No. 3,082,512, in which instead of the central bolt a hollow rivet is-used which is heated to red heat by way of electrodes and is then riveted by axial force accordingly. The valve parts can be damaged by the action of heat. Finally, in the case of the valve known from DE-OS 1 450 479 the valve parts are not provided with their own connexion. The component parts of the valves are pressed against the cylinder head of the compressor by a tensioning bolt passing through them. This design requires that the valve parts should be delivered loose and should be assembled only when attached to the compressor. In the process errors can occur, for example valve parts can be jammed between other component parts of the valve during clamping.